Critics of Trump's controversial statements, are "underestimating" the GOP candidate's ability to solve the nation's problems, Barrack said on "Squawk Box" from the sidelines of the CNBC/Institutional Investor Delivering Alpha conference in New York.

"Hillary is terribly competent. Nobody can say she's not competent," said Barrack, a member of Trump's Economic Advisory Council. "Her being sick is not an opportunity to pounce on her, in my view. It happens to everybody."

But the executive chairman at Colony Capital, with $24 billion in assets under management, said the election is a choice between "disruption, which is Trump, and status quo, which is Hillary."

Barrack, like Trump, made his fortune investing in real estate. He's known Trump since the 1980s, and spoke in support of the billionaire at the Republican National Convention in July.

In response to a question about criticism of Trump, Barrack said: "He's a warrior. He keeps moving."

When the presidential campaign shifts from personality to the issues in the upcoming debates, Trump is really going to shine with his ideas on immigration and battling ISIS, he added. "The bottom line is I think he's correct in most of those things.

Barrack, who described himself as an Arab-American Christian, said: "Radical Islam is a fundamental problem in the Middle East" that needs to be addressed in a more urgent manner.

Praising Trump as a businessman and consensus-builder, Barrack said the political establishment is the problem. "We have to bust the system somehow."

"I personal don't like the rhetoric," Barrack added. "But if he listened to me, he would be on "The Apprentice.' He wouldn't be the Republican candidate for president."